Hi Jim,

I was _mostly_ kidding about jettisoning the engine. The problem
is how to do a ballistic chute in a pusher _without_ first jettisoning
the engine. There is a problem with the chute streaming behind the
aircraft and getting into the prop! I've thought about twin chutes
deployed from pods in the wing, etc., but that has big problems if
the chutes do not deploy identically.

Jettisoning the engine _might_ be possible if you built the firewall
to attach to the airframe with some type of latching mechanism that
would unlatch with a lever. In a pusher the firewall is being pushed
into the airframe by the engine instead of pulled out of it, so the
main problem would be to support the weight of the engine, and provide
counter torque for the rotation of the prop.

The problem of the fuel lines could be dealt with by quick disconnects
similar to the ones now required in most states at gas stations. When
they pop apart, spring loaded balls stop the flow of fuel on both sides
of the disconnects. You could have a latch which holds them
together until your "jettison" lever is pulled.

The problems left are the control cables: Throttle, Mixture, and Prop.
It _might_ be possible to build an intermediate box which would transfer
force from one set of cables to a secondary set. The cables from the
cockpit controls would run to the box, and a second set of cables would
run from the box to the engine. The box would be designed to pull apart
during engine jettison.

The only thing left that I can think of is the heater hose for cabin
heat. An intermediate box with the hose for the engine on one side
and a hose to the cabin on the other should take care of that.

Have I left anything out? ;-)

Oh yeah. The cowl is attached to the firewall portion that
seperates from the aircraft, so it goes with the engine. Four
small air cylinders and a 10 cubic foot scuba pony bottle
with compressed air at 2000 PSI make sure that the firewall
seperates cleanly from the aircraft. The two chutes (big one
for the aircraft, and smaller one for the engine/cowl/firewall)
are stored between the firewall and the rest of aircraft and
deploy when they are seperated. The whole assembly is made
such that you can remove the cowl, support the engine, and
seperate the two parts for inspection.

When you pull the lever, the compressed air blows the firewall
off the back, seperating the fuel lines, control box, and
heater box, and exposing the chutes.

Could work, and would be a lot of fun to design and test ;-)

What do you think?

Don W.

Morgans wrote:
"Don W" wrote


I'd also like it to have a built in
ballistic chute system which jettisons the engine (to its own chute)
before deployment.


Welcome, Don!

Wow, you really want to jump in, huh? g

Realistically, getting the engine out sounds like such a complicated task,
as to be un-do-able in a plane of this size, and probably even in a much
larger size.

You have to sever the fuel lines/fuel system, in a running engine, and that
sounds like fire.

You have to get the engine mounts separated, and that sounds like explosive
bolts in a hot environment, and they need to be 110% reliable. Problems
there.

The engine has to have all of the other systems separate cleanly, and the
cowl get out of the way. Reliability problems, it would seem to me, since
they also have to be assured to not separate during normal operations.

How would it jettison? Rocket type of things, like an ejection seat? That
is a pretty volatile system, and it would have to put up with the difficult
environment of the engine compartment.

There is certainly more to consider, but that is enough for now, I think.

I have to ask, what is the payoff of having the engine separate? Less
weight for the chute? OK, but chutes can be made bigger to handle all of
the weight. Not having the heavy engine to worry about it shifting into the
cockpit during a parachute landing? OK, but the landing should be at a
relatively low speed, and that should not be a big concern. Cirrus seems to
have a pretty big engine, and I have not heard of any engine/cockpit
interactions that were a problem.

I think if you want a challenge to work on, look for something else. The
engine needs to stay right where it was put, IMHO. Work on a chute for the
bigger, heavier plane, perhaps.